Can't remove, move or create categories

[Kerwan]

Hi, I installed with success NodeBB on my VPS.

Here is the details :

• NodeJS v6.9.4
• NodeBB v1.4.2

But i can't remove, create or move any categorie. When i click on the "+" icon, nothing happen...

And by the way, i installed the plugin nodebb-plugin-poll but i have nothing more on my composer.

Thanks and sorry if my english is bad